05-20-2008 07:29 AM - edited 03-15-2019 10:46 AM
'm trying to enable T.38 Fax in my network environment using UC520. The setting is something like this:
Fax 1 -- UC520 -- CCM -- VOIP -- PSTN -- Fax 2
Cisco UC520 (using CME) is the originating gateway for fax 1 to send T.38 fax. It is going to the Cisco Unified Call Manager 5.0.4 through SIP trunk.
T.38 has been enabled at the remote terminating gateway, which is using a 3rd party gateway. The receiving fax machine, Fax 2, is currently able to receive fax from other normal fax machine (PSTN & VOIP), but not from Fax 1.
Currently normal voice call can be made from fax 1 (when FXS port is connected to an analog phone) to all the numbers in VOIP and also to all PSTN numbers (local&international). Incoming call can also be received in fax 1.
However, when testing fax call, both Fax 1 and Fax 2 are not able to receive/send fax to each other. In other words, If Fax 1 made a call to Fax 2, there is a ringing tone at the other end but it will just go idle after a while and unable to respond to the fax call.
Therefore, I need some help to check if the following configuration at UC520 is correct, or is there any other way to enable T.38 at the CCM? Currently only SIP trunk to UC520 is configured on the CCM.
Thank you in advance.
===
!
voice service voip
allow-connections sip to sip
no supplementary-service sip moved-temporarily
no supplementary-service sip refer
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw
sip
registrar server expires max 3600 min 3600
localhost dns:BWTC.local
!
!
voice class codec 1
codec preference 1 g711ulaw
!
voice-port 0/0/0
ring cadence pattern01
description **FXS Port To Fax Machine**
station-id number 13324400
!
dial-peer voice 2 voip
description **T.38 SIP Trunk To CCM**
destination-pattern [0-9].......T
session protocol sipv2
session target ipv4:80.95.220.110
incoming called-number .T
dtmf-relay h245-signal
codec g711ulaw
fax-relay ecm disable
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw
no vad
!
dial-peer voice 10 pots
destination-pattern [0-9].......T
fax rate fax
no digit-strip
port 0/0/0
forward-digits 0
!
!
sip-ua
registrar ipv4:80.95.220.110 expires 3600
!
====
05-26-2008 04:16 PM
Could you verify if the The service parameter "Strip G.729 Annex B (Silence Supporession) from Capabilities is
set to TRUE on both servers
05-26-2008 05:26 PM
What do you mean by your statement? I don't understand
05-26-2008 06:43 PM
That is a parameter in CCM Service PArameters
Could you please provide detail CCM traces
to see where might be the failure
Include calling, called number, timestamps and behaviour
05-27-2008 01:07 AM
The design is like this:-
Fax1>>linksysspa2102>>CCM>>SSW>>GW>>PSTN/Carrier>>Fax2
I noticed that the CCM software MTP is not supported T38 fax relay. So, we introduced the hardware MTP that is Cisco AS5350XM which is also doubly support the T38.
Regarding the DP & MRGL, I have read that "any endpoint whether ATA or trunk that participates in the T.38 fax call needs to use a MGRL that includes the 'hardware' MTP". We have already did that, put the hardware MTP in the Multicast_MRGL and assigned it to Muticast_DP to the ATA. For the SIP trunk, we put the hardware MTP in the Unicast_MRGL and assigned it to BWTC_PSTN_DP.
But not only fax calls failed, the voice calls cannot be made as we checked the MTP box, and assigned only hardware MTP on it.
For local fax, the fax calls is successfully made. We just untick the MTP box at the SIP trunk, and fax calls can be made.
But for international calls that need early offer, i think we need the MTP for the call to be started as voice than switched to T38.
For international fax, when we are using software MTP in the DP for endpoint and SIP trunk, MTP are checked at the trunk, I notice that the calls are through, the fax tone is detected, the fax machine shown that:-
1) fax response recognized
2) determine exchange rate 14400bps
Then, the connection is lost. Suppose for successful fax, after No.2, it will fax the contents to the remote side.
Can you take a look on the CCM traces I've attached to you? There is incoming message from SSW to the CCM "request time-out". Is it the calls have been established and getting drop by any party or else?
Noted that the fax calls are from 13324220 to international number 0060380243462
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